silane

/sil"ayn/, n. Chem.

1. Also called silicon tetrahydride. a gas with an unpleasant odor, SiH₄, soluble in water: used as a doping agent for semiconductors in the production of solid-state devices.

2. any of a class of silicon hydrides analogous to the alkanes.

[ < G Silan (1916); see SILICON, -ANE]

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or silicon hydride

Any of a series of inorganic compounds of silicon and hydrogen with covalent bonds and the general chemical formula Si_nH_{(2n + 2)}.

Silanes are structural analogs of saturated hydrocarbons (see saturation; alkane) but are much less stable. All burn or explode when exposed to air and react readily with halogens or hydrogen halides to form halogenated silanes and with olefins to form alkylsilanes, products used as water repellents and as starting materials for silicones.

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▪ chemical compound

also called  Silicon Hydride,  

      any of a series of covalently bonded compounds containing only the elements silicon and hydrogen, having the general formula Si_nH_{2n + 2}, in which n equals 1, 2, 3, and so on. The silanes are structural analogues of the saturated hydrocarbons (alkanes) but are much less stable. The term silane is extended to include compounds in which any or all of the hydrogen atoms have been replaced by other atoms or groups of atoms, as in tetrachlorosilane, SiCl₄.

      Silanes have been prepared by the reaction of magnesium silicide (Mg₂Si) with acids or by the reduction of silicon chlorides with lithium aluminum hydride. All the silanes burn or explode upon contact with air, and they are decomposed by alkaline solutions with formation of hydrogen and hydrous silica. Upon heating, the silanes decompose into hydrogen and silicon; they react with the halogens or hydrogen halides to form halogenated silanes, and with olefins to form alkylsilanes.

      The simplest silane, monosilane (SiH₄), is also the stablest; it is a colourless gas that liquefies at -112° C (-170° F) and freezes at -185° C (-301° F). It decomposes slowly at 250° C (482° F), rapidly at 500° C (932° F).

      The instability of the silanes results from the reactivity of the silicon-hydrogen bond; derivatives in which all the hydrogen atoms have been replaced by organic groups, such as tetramethylsilane, Si(CH₃)₄, resemble the saturated hydrocarbons. The compound dimethyldichlorosilane, (CH₃)₂SiCl₂, is important as the starting material for the dimethylpolysiloxanes, members of the silicone family of polymers. Chlorotrimethylsilane and vinyltrichlorosilane are used to impart water repellency to numerous materials such as cloth, paper, and glass.

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